A chloride channel is an ion-transport membrane protein for transporting chloride ions (Cl−). It has been reported that various kinds of chloride channels are present in the cell membrane of nerve, muscle and epithelium, and they are involved with various physiological functions and cytophylaxis mechanisms.
For example, a chloride channel cloned from crampfish's electric organ and named ClC-0 was later found to form a large family (ClC family). Examples of ClC family are: ClC-1 present in the skeletal muscle of mammals; ClC-2 present in the epithelium of various organs; ClC-3 and ClC-4 distributed in hippocampus, cerebellum, etc.; ClC-5 present in lung, kidney, etc.; ClC-6 and ClC-7 present in brain, testis, skeletal muscle, kidney, etc.; and ClCK-1 and ClCK-2 specifically shown only in kidney.
It is generally said that various channels are involved with a number of diseases. It is generally believed that the dysfunctioning of these channels or the existence of regulation defects in processes that activate such channels may play an important role in the pathogenesis of such diseases and illnesses. As a result, a compound, which opens various channels and assists regulation of electrophysiological function of cells, could have important therapeutic and prophylactic abilities for treatment and relief of such conditions.
It is inferred that a ClC-2 channel therapeutically plays an important role in cystic fibrosis, which is an autosomal recessive inherited disease best known in the Caucasian race (Cuppoletti et al., American Journal of Physiology. Cell Physiology, 281(1), C46-54, 2001; Joo et al., Biochemica et Biophysica Acta, 1446(3), 431-437, 1999 and Schwiebert et al., Proc. Natl. Acad. Sci. USA 97(7), 3879-3884, 1998). However, the details of other roles are not known very well.